package com.demo141_环形链表;

 class ListNode {
     int val;
     ListNode next;
     ListNode(int x) {
         val = x;
         next = null;
     }
 }
public class Solution {
    public boolean hasCycle(ListNode head) {

        if (head==null||head.next==null){
            return false;
        }

        ListNode slow =head;
        ListNode fast =head.next;
        while (slow!=fast){
            if (fast==null||fast.next==null){
                return false;
            }
            slow=slow.next;
            fast=fast.next.next;
        }

        return true;
    }
}
